Really small insect
Mymaridae is a family of wasps commonly known as fairy wasps.
They are a very old group of tiny wasps. When I say tiny, I mean really small. The smallest species don't even reach 0.15 mm in length. They are parisitoid wasps and lay their eggs inside the eggs of other insects.
Fairy flies can be found in all temperate or tropical regions and are actually very common, but good luck spotting them.